Practical and Scalable Method for Manufacturing AZD4604, A Potent and Selective JAK1 Inhibitor

The development of a scalable process for the manufacture of a potent and selective JAK1 inhibitor intended for the inhaled treatment of asthma is described. The initial milligram-scale synthetic protocols were unsuitable for larger-scale synthesis, which led to a systematic evaluation of the reaction conditions to identify the optimized reaction conditions for the Suzuki/Buchwald–Hartwig coupling, deprotection of the tosyl group, chemoselective nitro-reduction, and developing mild conditions for the amide coupling of a sensitive amino acid. This work also highlights mitigating critical issues associated with the synthesis of poorly soluble compounds, slurry-to-slurry metal-catalyzed coupling protocols. The optimized amide coupling conditions using chiral amino acid produced the desired active pharmaceutical ingredient (API) in high overall yield and good high-performance liquid chromatography (HPLC) purity.